In 2004, high-entropy alloys (HEAs) emerged as a fascinating class of materials, consisting of multiple principal elements combined in nearly equal proportions. The unique composition of these alloys results in a high level of chemical disorder, or entropy, leading to exceptional properties such as high strength, ductility, and resistance to wear and tear, even under high temperatures. Researchers have dedicated considerable efforts to developing novel HEAs, particularly in the realm of electrocatalyst materials, aiming to enhance their performance.
Understanding the atomic-level surface structure of HEAs is crucial, as surface properties often dictate the catalytic activity of materials. Consequently, scientists are keen on establishing the correlation between the atomic arrangement and the catalytic properties exhibited by HEAs.
Recently, a collaborative research team achieved a significant breakthrough by creating an innovative experimental platform capable of controlling the atomic-level structure of HEAs’ surfaces and assessing their catalytic properties. Their findings were published in the prestigious journal Nature Communications on July 26, 2023.
The team focused on a specific alloy called a Cantor alloy, composed of a combination of elements (Cr-Mn-Fe-Co-Ni), and deposited thin layers of it onto platinum (Pt) substrates. This configuration allowed them to create a model surface for investigating the oxygen reduction reaction (ORR), a crucial reaction in many electrocatalytic processes.
Advanced imaging techniques enabled the researchers to scrutinize the atomic-level structure of the Pt-HEAs’ surfaces and analyze their ORR properties. The results were striking, showing that the Pt-HEAs’ surfaces outperformed surfaces made of a platinum-cobalt alloy in the ORR. This finding suggests that the specific atomic arrangement and distribution of elements near the surface, forming a “pseudo-core-shell-like structure,” significantly contribute to the excellent catalytic properties of Pt-HEAs.
The team emphasizes that their findings have broad applicability, not only for various constituent elements but also for other nanomaterials. Their newly developed experimental platform serves as a potent tool to unravel the intricate relationship between surface microstructures of multi-component alloys and their catalytic properties. This knowledge extends to HEAs with different constituent elements and ratios, providing valuable data for materials informatics. The platform’s potential reaches beyond electrocatalysis and extends to various functional nanomaterials applications.
Looking to the future, the research group aims to expand the platform’s practical applications by utilizing Pt-HEA nanoparticles, aiming to increase electrochemical surface areas and further improve catalytic performance.
Source: Tohoku University